The Center for Musculoskeletal Research (CMR) is a joint program between Oak Ridge National Laboratory (ORNL) and the University of Tennessee (UT). Under the leadership of Richard D. Komistek, PhD as the Principal Investigator (PI), researchers in the CMR propose to develop accurate computational models that could eventually be used to predict in vivo contact stresses at the bearing surface interface (disc and facets) of the vertebral bodies and sacrum of the lower back and assess surgical outcomes in terms of reduction of pain after fusion or disk replacement surgery. The main goal of the proposal is to develop an accurate computational methodology that involves: 1) deriving and implementing in vivo kinematics using X- ray fluoroscopy, CT scans for bone modeling and MRIs of the lumbar spine for soft-tissue evaluation as input to our mathematical models;2) computing the forces at the spine interfaces using a mathematical model;3) computing the deformation and stresses in the intervertebral discs under normal and degenerative disc conditions (pre-surgery stage);4) developing an in vivo computational modeling capability for the lumbar spine structure;and 5) developing a methodology to correlate the computational and clinical data. The model could eventually be used to predict in vivo contact stresses at the bearing surface interfaces, ligament forces that provide constraint, and muscle forces (and tendons) of the vertebral bodies of the lower back. This model would allow us to assess surgical outcomes in terms of reduction of pain after fusion or disk replacement surgery, and could be used in the future design and validation of spinal prostheses. We will team with clinicians at Vanderbilt University to correlate and validate the clinical and computational data. It is estimated that 80-90% of the U.S. population will experience lower back pain at some point in their lifetime. It is the most common work-related medical problem in the United States, and the second most common reason for doctor visits behind the common cold. Lower back pain is the leading cause of disability among people ages 19-45 and is the leading cause of missed work days. People with chronic back pain account for 80% of the cost of treatment in workers compensation claims. Longer life-spans and an increasing proportion of middle aged and elderly people make lower back pain an increasingly significant problem. The cost in terms of treatments and missed work is billions of dollars annually. From an orthopedic perspective, the spine is the fastest growing segment of the market. New treatments, including total disk replacement, and facet arthroplasty, will provide alternatives to fusion, but there is a need to do more biomechanical research and develop appropriate tools to develop predictive models, assess safety of the devices, and make this knowledge and the tools available to the orthopedic community.